Mosquito Borne Diseases

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In recent years, there has been much focus on the incidents of mosquito borne diseases, particularly West Nile Virus and Eastern Equine Encephalitis. There are steps you can take to reduce the presence of mosquitoes on your property – mainly reducing standing water. Even a little bit of standing water – what might accumulate in the saucer of a plant pot after a rainstorm – can be an active breeding ground for mosquitoes. Other places that could be good mosquito breeding grounds include:

  • Discarded tires
  • Rain barrels, buckets
  • Abandoned boats
  • Clogged roof gutters
  • Bird baths
  • Abandoned or untreated swimming pools, wading pools
  • Ceramic pots, empty cans
  • Wheelbarrows
  • Anywhere water can collect!

Section 19-13-B31 of the Connecticut Public Health Code states that “no person shall maintain or permit to be maintained any pond, cesspool, well, cistern, rain barrel or other receptacle containing water or accumulation of stagnant water in such a condition that mosquitoes may breed therein or may injure health or cause offense to other persons”. Some things you can do to avoid mosquito bites include:

  • Minimizing time outdoors at dusk and dawn.
  • Ensuring door and window screens are tight-fitting and in good repair.
  • Wearing shoes, socks, long pants and long sleeved shirts. Clothing material should be tightly woven.
  • Using mosquito netting when sleeping outdoors.
  • Using mosquito repellent when necessary - in a safe manner according to the label instructions.

West Nile Virus
West Nile Virus is a mosquito borne viral infection that is transmitted by the culex species of mosquito. Most people infected with the virus experience no symptoms; however, the disease may be serious or even fatal.

In 1999, West Nile virus (WNV) was found in dead birds in coastal towns of Connecticut from Greenwich to Madison. The same year, it was also found in New York, New Jersey, and Maryland, marking the first time this virus was identified in North America. Within 3 years it spread across the country and remains an important cause of mosquito transmitted disease.

West Nile virus follows a complex life cycle in nature. Wild birds serve as the reservoir for WNV. The virus is transmitted among wild birds primarily by mosquitoes. Infected mosquitoes can also transmit the virus to other animals and people. While most birds do not become sick if infected, some do such as crows and blue jays. Among domestic animals, horses are the most susceptible to disease.

The State Mosquito Management Program, an interagency working group, was established to work with local governments in response to the threat of diseases that are transmitted by mosquitoes. The principal diseases of public health importance in Connecticut are eastern equine encephalitis virus (EEE) and WNV.

The Mosquito Management Program is based on an integrated pest management approach. It aims to minimize the risk of disease transmission to people in an environmentally responsible way. The approach includes a combination of surveillance, education, mosquito control, and personal protection measures. Control recommendations reflect a graded response in proportion to the threat.

Surveillance activities currently include monitoring mosquitoes, domestic animals and poultry, and humans. To monitor for WNV infection in people, the Connecticut Department of Public Health (DPH) provides laboratory testing of cerebrospinal fluid and blood from persons hospitalized with illnesses consistent with WNV infection.

Exposure to mosquitoes and the risk of acquiring WNV infection varies by season and geographic region. In Connecticut, the risk is highest during August and September. Among persons who travel to other states and internationally, the possibility of infection exists throughout the year.

Eastern Equine Encephalitis
Eastern Equine Encephalitis (EEE) is a rare but serious disease caused by a virus that is transmitted by mosquitoes. EEE virus occurs in the eastern half of the United States where it causes disease in humans, horses, and some bird species. Because of the high mortality rate, EEE is regarded as one of the most serious mosquito-borne diseases in the United States. To date, there has never been a documented human case of EEE in Connecticut, although the virus has been found in trapped mosquitoes. Helpful Resources